In recent years, there has been an increasing demand for a long cruising distance and a short charging time of a high voltage battery in a vehicle that runs on a high voltage battery as a power source, such as an electric automobile. In this respect, the high voltage battery for driving a vehicle may be charged with electrical power obtained by solar power generation.
When the high voltage battery is charged with the electrical power obtained by solar power generation, a boost DC-DC converter and a relay to boost the voltage of the electrical power to a high voltage need to be driven, however. Thus, when good sunlight is not available, the power consumption for driving a boost DC-DC converter or the like becomes greater than the electrical power obtained by solar power generation. As a result, there is a concern that the high voltage battery may not be charged.
In Patent Literature (hereinafter, referred to as “PTL”) 1, a configuration is employed in which an electric double-layer capacitor is charged with the electrical power generated by a solar cell, and a charger operation command signal is output to a charger to re-charge a battery with the electrical power in the electric double-layer capacitor when a terminal voltage of the electric double-layer capacitor exceeds a breakdown voltage of a Zener diode. Accordingly, since the charger is in a non-operation state when the terminal voltage is equal to or lower than the breakdown voltage of the Zener diode, it is possible to limit the power consumption in a circuit to the minimum, and to efficiently use energy.